"Eliminate muda, mura, muri* completely."

When Taiichi Ohno became manager of Final Assembly in the Manufacturing Department of Toyota Motor Corporation in 1945, he faced a huge challenge. Toyota had become highly inefficient during the Second World War, and Kiichiro Toyoda's Just-in- Time system had collapsed completely.

Just-in-Time dictates that parts are delivered to the right part of the assembly line, at the right time and in the right amount. However, for this to work effectively, Ohno realized that another factor had to be controlled: quality. Parts must be flawless and defects must be eliminated before progressing along the line. This is when jidoka, the second pillar of what would later become the Toyota Production System, entered the picture.

In seeking to re-implement Just-in-Time, Ohno turned to a much earlier invention of Kiichiro's father, Sakichi Toyoda — a loom which would stop automatically when a thread broke. He realized if this jidoka (self-regulation) could be applied to machines in the car plant, not only would product quality improve, but workers would also be able to supervise multiple machines, thus increasing efficiency.

At each worksite, groups were formed to find ways to rationalize operations, always bearing in mind Ohno's words, "eliminate muda, mura, muri completely." Out of these discussions came the Kanban system as a means of improving communication between processes and the andon system. The andon cord empowered workers to stop the entire production line if any complications arose, thus adding a human check to jidoka. Andon boards also informed workers of the whereabouts and nature of the problem.

Ohno was unconcerned about the consequences of stopping the entire line, knowing that instant identification of the problem would lead to improvement of the processes in the long-term.

In 1970, after years of experimentation and strenuous team efforts, the entire system — with all the innovations and improvements that had been added to it over the years — came to be known as the "Toyota Production System." It was a result of the spirit of kaizen (continuous improvement), which the plant workers shared and which the Toyota family around the world continues to share today in all aspects of its work.

Never pass defective items to the next process. Assembly line worker pulls the andon cord.